(1) Field of the Invention
This invention relates to a lithotripter having a transducer for generating focussed ultrasonic shock waves and having an axis and a focus, and at least one diagnostic X-ray imaging system for locating a concretion or tissue to be destroyed at the said focus, which system may be arranged on a frame which can be pivoted about an axis in various image planes for locating purposes.
(2) Description of the Prior Art
Examples of known lithotripters in which location of a concretion, e.g., a kidney stone, which is required for every lithotripsy and which precedes the destruction of the concretion by ultrasonic shock waves is carried out with an X-ray system are disclosed in DE-GM 8515656, DE-GM 8528785 and DE-GM 8534425.
For location of this kind at least two planes of irradiation are needed. What are normally used for this purpose are the so-called AP projection and a projection pivoted through 30.degree. from it. Once the concretion to be destroyed has been successfully located, its spatial co-ordinates are found electronically. Complex electronic and mechanical systems then move the ultrasonic shock wave transducer until its focus lies in the region defined by the spatial co-ordinates which were found. Only then is it possible and medically sensible for ultrasonic shock waves to be applied.
One disadvantage of such known lithotripters is that once the concretion to be destroyed has been located with the X-ray system, the focus of the shock wave transducer must first be moved so that it is positioned on the concretion, if the patient is not to be moved from the position which he/she occupied when the concretion was located. Another disadvantage is that although there are many conditions where ultrasonic location of the concretion is indicated, this type of location is not possible with the known units using X-ray location.
The main object of the present invention is to provide a lithotripter in which X-ray location and ultrasonic location of the concretion to be destroyed are possible simultaneously or independantly of each other with no change in the position of the patient. It must be possible for real-time X-ray location to be carried out both during the shock wave application and during the adjustment of the locating systems.